Although I'm not a LR user, I was excited to see the new editing features, as they will be essentially the same as the next version of ACR that will be part of PS CS6 (all guesswork on my part of course, but as Adobe has always done this previoulsy I don't think it's much of a leap of faith to make). A few features and changes that stood out for me:

They've re-vamped the basic tools, and have a new Process Version 2012;

Localised adjustments now allow you to adjust white balance and noise reduction;

It seems that they have done away with tradtional Exposure (replacing it with Brightness's functionality), and moved towards Photoshop's Levels controls (Blacks, Gamma, Whites), except that (interestingly) the end controls have postive AND negative settings. It will be interesting to see how this affects photographers who think in terms of stops of exposure compensation. Overall, it seems a logical step, although moving from one PV to another may be frought with tears.

It looks like Recovery has been revamped too, which a lot of people will be happy about.

I assume ACR will allow using either the old or new process to accomidate files that were adjusted using the current process. If you want to migrate old RAW files to the new process will this require starting over?

To follow up on Eric's post, yes, at some point in time (yet ro be determined) LR 4 GM and ACR 7 GM (for PS S6) will match up and have equivient functionality/renering. It's LR's nature to do public betas (for good or bad) but NOT Photoshop's behavior. So, if you want to see what will be in ACR 7, check out the LR 4 beta...just note that things are subject to change since LR 4 is still considered "beta" which means Adobe is free to make certain changes or alterations. Also note that since LR 4 is considered beta (not RC or GM) things are subject to change/refiement when the final versions ship.

I'm quite satisfied with a new automatic recovery procedure. Just that ... it will probably raise new posts about mismatching between camera profiles and in-camera jpegs, because when a photo has blown parts, recovery kicks in automatically. Also, in some (rare) cases I would just want to have it off ... so maybe having a whites slider with 'auto' check box or something similar would be a better solution ... Anyway, finally I can say that dealing with highlights is now even better than in Canon cameras / software, which have similar solution for at least 5 years ...

Since R and B channel, that can be blown by WB, are now also recovered, resulting hue of blown parts is now different than with PV2003/2010. If G and B are blown, resulting hue is around 200 deg (instead 180 previously), which looks more natural for parts of blown sky. If R and G are blown, resulting hue is around 40-50 (instead 60 previously), which is ok for blown areas around sun in sunset photos etc but ... in some rare cases there can be blown foliage colors and it doesn't look particularly good when blown green turns light brown ... So a slider to deal with hue in blown parts for brush tool would be fine somewhere in the future, because painting that areas with some color doesn't produce desired result ...

Getting rid of defaults from the past (brightness +50, contrast +25, blacks 5,. medium-contrast curve) is also nice, as it didn't make any sense with camera profiles

I'm also glad that clarity is now usable for me, so I don't have to apply wide radius USM in PS anymore ... The same with highlight & shadows tool, that is now implemented here ... etc ...

The Whites slider can be used to "blow out" the highlights if desired (i.e., drag to the right). It will not be exactly the same as in PV 2010, though, with respect to one color channel clipping before the other (and the hue shifts that this normally entails).

Your point about the Camera Matching color profiles is well taken, though I felt having smoothly recovered highlights was going to be a win in most cases.

Yes, I noted that whites slider can be used and the result is a bit different than in PV2010 ... not a big deal I suppose (and we still have PV2010 available if needed)

Just, from my remembering (not quite sure anymore - maybe I'm wrong), position of whites slider that will return similar result as PV2010 depended on particular photo and amount of blown highlights

There was also a small issue in violet highlight range - with my test photo containing no blown highlights, there was some mismatch between output using camera profile between PV2010 and PV2012. With PV2010, my profile matched DPP output almost perfectly, while with PV2012 there was some (slight) difference in that range. Will take a look at that again when ACR 7 becomes available, because LR doesn't run on my XP ...